Variable pitch propeller



Jan. 3l, 1950 E. R. LOCHMAN 2,496,169

VARIABLE PITCH PROPELLER Original Filed Aug. 8, 1942 6 Shets-Sheet 1 A7' TOPPA/F545.

Jan. 31, 1950 E; R. LocHMAN 2,496,169

VARIABLE FITCH PROPELLER Original Filed Aug. 8, 1942 6 Sheets-Sheet 2INVENTOR:

Kf 3. EMM. 2 och/M4N BY r-gL/r, M sp-IM A T TO R NEY.

` Original Filed Aug. 8, 1942 Jan. 3l, 1950 E. R. LocHMAN 2,496,169

VARIABLE FITCH PROPELLER 6 Sheets-Sheet 5 "mi L -Is l l AT TORNEY.

Jan. 3l, 1950 E. R. LOCHMAN VARIABLE FITCH PROPELLER Original Filed Aug.8, 1942 6 Sheets-Sheet 4 INVENIOR. EMM, Z och/Avv mf ATTO?? Nm/e.

Jan. 31, 1950 E. R. L ocHMAN VARIABLE FITCH PROPELLER 6 Sheets-Sheet 5Original Filed Aug. 8, 1942 INVENTOR.

y-M s M A TToRdvly.

Jan. 31, 195o E R CHMAN 2,496,169

VARIABLE PITCH PROPELLER Original Filed Aug. 8, 1942 6 Sheets-Sheet 63W' $7/ afs 4oz 37 ai L! ab 376 INVENroR `77 EMM. f? oc/MAM A TTORN'MS,

Patented Jan. 31, 1950 UNITED STATES PATENT OFFICE 6 Claims. (Cl.P10-160.43)

This invention relates to propellers and meth ods oi' propellermanufacture, and more partlcularly to a controllable pitch propeller forvarying and controlling the pitch of the propeller in accordance withthe operating conditions.

The principal object oi this invention is to provide a simplifiedconstruction of a controllable pitch propeller. adapted for massproduction, and adapted to be used and mounted on the engine shafts o!the present day airplane engines, for immediate production.

A further object oi the present invention is to reduce the number oioperating parts, to avoid parts requiring very costly machiningoperations.

It is a further object of the present invention to provide a system iorvarying the pitch of a propeller which may be operated automatically atconstant speed by a speed responsive governor coacting with an automaticswitching device directly controlling the device for ieatherlng thepropeller blades.

A further object oi this invention is to provide a. system for varyingthe pitch of the propeller permitting a wide variation of adjustment oisaid pitch by selection oi the operator and in co-action with theautomatic control. and further per mlttlng adaptation for various makesand sizes of airplanes and usable as a. master control ior a series oiengines and propellers. as well as a single engine propeller control.

ieathering hub construction disclosed herein, it is a further oblect ofthis invention to improve propeller construction hy strong internalreenforcements oi' a hollow blade and by changing the shape of the bladeto avoid extreme forming strains and by providing a method of formingthe blade in two halves and leaving a hollow passage from the 'root tothe tip oi the blade in the form of a combination spar ior the Purposeof aidingin the consll'uction of the blade as wellasincreasingitsstrengtmrigidityandthrust capacity.

A considerable number of accidents have cccurred traceable topower-failures and consequent failureof the blade pitch controllingapparatus. especially through lack o( pressure in the iluid system ofthe control. In addition, the oil becomes cold and sluggish in theextreme cold of high altitudes. These power-failures for the controlsystem oi the propellers increase greatly during actual lightingconditions in war service. It is therefore oi great importance that amanual safety control be provided. In addition, my invention providesfor constantly locking the pitch 2 of the blades and rendering theiractuating connections irreversible whether adjustment is eiiected byautomatic control, by semi-automatic control. or by hand.

The manual or h'and control further provides ready means for testing thepitching mechanism at any time without power application. This is oi'considerable assistance in ground testing.

This is a. division oi' my co-pending application, Serial No. 454,146,filed August 8. 1942, and discloses unclaimed subject matter disclosedand claimed in my co-pending application Serial No. 130.918, ledDecember 3, i949.

Further objects ci' the invention will appear in the followingdisclosure. The means by which the objects of the invention are obtainedare more fully described with reference to the drawings. in which:

Figure l is a top plan viewof the propeller assembly, with parts brokenaway to show part of the hub section and other operating ports in crosssection, as well as showing the nose section ci the airplane engine andthe manner in which the propeller is attached thereto.

Figure 2 is a rear elevation of the propeller assembly, with parts cutaway showing across section oi' the operating parts on line 2-2 oiFigure 1, but omitting the nose section oi the airplane engine, whilethe propeller hub has parts broken away to show a part in cross section.

Figure 3 is a fragmentary view o! a single vblade assembly In itsrespective hub socket. showing in radial section the respectiveoperating parts and certain welding Joints, a part otthebladeappearinginelevation. g

Figure 4 is a. side view of thev essential parts of an arc weldingdevice showing two halves of a propeller in cross section as-preparedforarc welding according to the process herein disclosed.

Figure 5 is a side view ot a Jlgshowing the cross section ot a propellerprepared for brazing in a brazing furnace.

Figure 6 is a fragmentary cross sectional view oi a hub assembly on line6--8 of Figure 3. showlng the rack and pinion control of a propellerblade.

Figure 'l is a iront elevation oi a propeller blade showing theessential parts ot the construction, including the core shaft and theconnecting internal spar.

Figure 8 is n plan view o! the blank for tormlng a hall' section of apropeller blade.

Figure 9 ls a perspective cross sectional view oi propeller sectionsshowing the intemai spar in 3 4 half section as prepared tor arc weldingthe halt ing from the spirit o! the invention. especially blades showninFigure 4. in iltting it to various types of airplanes and lor Figure 10ls a pian view of a core die for iormtheir varying requirements andservices. ing the spar with a surface for attaching the Several of thefeatures ot my invention are blade sections according and conforming tothe 5 usable independently of each other and in varpitch oi' the blade.ious combinations. being separately described Figure a is a fragmentaryelevation o! the and claimed. I shall hereinafter summarize bottomsection of the core shaft showing the these tentures and theirproperties.

spar and a half section of the blade attached For assistance inanalyzing my disclosure. I

thereto. i0 may state that the complete apparatus herein- Figure l1 is aDian view of the spar blank, after to be described includes:

ShOWiDS welding Slots- 1. A variable pitch propeller having impor-Flgure 12 is a cross section of a half spar pretant features oi' hubdesign, irrespective of the pared from a hal! section of said spar blankfor particular blades used therein.

use as shown in Figure 9. l5 2. A novel and improved propeller bladestruc- Figure 13 i8 8- Dlll View 0f the bOttOm SBC- ture and process ofmanufacture which is partlon of the Core Shaft Shwlng the bottomSecticularly adapted for a variable pitch propeller. tion 0i' the SPM'Welded thelelobut may be used in any propeller oi' variable Fllire 14 isa fragmentary r0SS Section 0f the pitch or otherwise. and irrespectiveof the parroot of the blade showing the relative parts o! go ticuigr hubor pitch varying mechanism.

the core shaft, spar and blade section welded 3. A novel pitch varyingmechanism usable and brazed together. irrespective oi' speciilc blade orhub design and Figure 15 is a fragmentary cross Sellfflnal havingpeculiar advantages in the way oi' isoview of the same parts as arrangedfor arc weldiating conn-Qi parts from the noce of the plane, and furtheradvantages in that it is applicable Figure 16 is a cross section on lineiS-IB ot to existing planes in the limited space available Figure 13,with parts broken away showing the in such planes,

DOSltiOll for the end fillers. welded in place to 4. A variety ofelectrical controls for effecting showing Spot Welding 101' rigidlyCOlmeCting the 30 irrespective (at least to some extent) oi the par-Figure 17 1S 8 frmentary rear elevation 0l' controls providing formanual and automatic a large composite bail bearing for transmittingpitch adJustment, and providing tor limitation motion between WO Sets 0frk and Pinion oi' the automatic pitch adjustment either to pariSSlOllS101' fethelln! the DIODellr blades 35 tlcularly determined incrementsoi' advance in a Figure 18 is a cross section on line ll--Il oi' givenoperation or to a particular overall range Figure 17. of' movement.subject to regulation by the op- Figure 19 is a diagrammatic plan viewof the @raton various apparatus tor controlling the pitch ot 5. Theinvention comprehends the use in any the Propeller bldes. mllllldln aWiring dlgrm U adjustable blade propeller `organization oi' anConnecting Said relative Darts Ol hnd as Well indicator which willvisually show at all times as automatic ienthering o! the propellerblades. to the puoi: the exact pitch adjustment of his Figure 20 is awiring diagram schematically bladen illustrating partially in sideelevation and par- 6. The invention provides means whereby. irtially invertical section the parts shown in plan respective of the source oi'power for normal proin Figure 19. and further illustrating the winneneuer blade pitch adiustment. the adjustment connections to such parts.two oi' the switches may be eirected manually in the event of powershown in side elevation being also illustrated in fiiure, p P1311 7. Theinvention contemplates speciilc im- Figure 21 is a view Partially inSide elevation 50 provements in various pieces of apparatus. with andPartially in Section. Showing an alternatively particular reference tothe governors and switches usable iluid motor attached to the rack barusedin the system and the circuits employed to actuate the ieatheringmechanism. therein,

Figure 22 is a view in side elevation of a fric- Reference will first bemade to Figures l and 2. tion brake. coupled to the motor operated wormwhere I have illustrated the: drive to prevent overrun in thei'eathering ot Propeller assembly-The propeller assembly the Propellerblades. comprises a hub 15 mounted upon and driven Figure 23 is anenlarged detail view oi the by a propellershait lll, which, insomeinstallagovernnr in cross section on the line 21-2! of tions, may alsocomprise the engine shaft. but Figure 24. w which. in the device asillustrated. is driven at a mure 24 i8 fragmentary View 0i' the 80V-reduced speed from the engine shaft l0' through ernor in horizontalsection on the line 2l-2| oi' conventional reducing gearing (notspeciilcally 23. illustrated) horned in the casing which is shown Figure25 is an enlarged detail view. partially in plan in Figure l surroundingthe engine shaft in side elevation and Dartiaib in section, of the gg iland the propeller shaft ll.

which. in accordance with conventional practice.

that various changes and moditions may be into the hub by the nut i9secured to the end o! made in the Structure disclosed without departthepropeller shalt.

radial 1:59.11 bearings nl! 'with tlielr o'u'ter Araces A The "s'everl*'iecl'bed B'S m'unbed 'in seriesfnttiefrootseticn II 'Stoffthe-propeller core shaftare :held thereon '-by the nut H screwed to'ftheIin`nered-til` the eoref'shaft. The-core shaft, in turn, together withall of the partsabove described, `is then Flly-tfrlil'iore'dto the bladeskt Eli-ofthe hub TB'by-'tlienut f I I-andlock ntfFZ. l

`In-lieu o'fakey for positively -xing'the' several propeller 'coreshafts sito their respective pinions 95"'-to'assure vopera-tion` inexactfunison, I'may use pms vrhih'rjet'arflly'from 'the'core Lshaftshoulder-1H'. 'asxshown inFigures "1. 10a yand. The '15in ifi primarily'relied upon to :locate the parts vhilepn's lljprovldesupplementaltdrquetrasmlttlng'strenth. t

te'th of the"plnion9`5 andithete'eth'of the 'il must be set -in'precisely the `same position 'for all threeBladesjand this 'positionispermanentlyhldby'the Set-pin 1li, so"that all blades may beiailrenoutad're-'mserted and matched precisely' atfth'eir pitch' angie.

rInllersetfting the radial: bores WB for receiving the Bladesare 'bores'il' m axial alignmen'tiw'lth the propeller shaft 'andboredtopreciserymtch Sammies-Mirto accomplish the preclslon between titleVpiniors "85 'the fdls 8 l ,'wliich re'clp'dcate "in 'the "tores' "8|"and sreccimected withtue;pressure 'disk "an by'up-' settln;tleir're'dueed ends'ag'aistlthe inner surfaeeof'tliepressureuisk'about'the holes in .the pressure 'disk through whihthe reduced-en`ds cfftireraclfs al :extend (heure ci.

tthelrforward endsl22' the racksl. are connectei for unitary-movement byanannular -plate i2 peturesto receive the .reduced and threaded forwardends f theracksl. -Nuts L23 securely olax'np the annulariplate''! to therespective racks. The annular plate-mayV be=guidedfor sliding l movementalong -the :propeller vnut 18 to which its central'openug83may betted(Figure `land Figure-6). -As theannular1plate 82 moves outwardly i alongthe Vpropeller mit 19 y it will encounter-the pressure-cap 34 which: isurged rearwardly -upon the-nutfbyazpowerful Icornpression-spring B6seated .in the nose -cap B1 'bolted tothe hub. Thisfspring raids .iniresistlng thrust of -thepropeller bladesv in their extremefeathering;position: and consequent! y fasssts in returnin'gY the -blades.fromfsucheictremefeathering position. The'four holes'l' providedin' thepropeller nut-aretd-fa'eiltatetheuse o'f a'lever-'lor tightening th'emitonitsshaft, wh'erebyto positlon'the 1.1 and 18 which assure :correcttracking -n`f the blades.

Transmission casing Z1`lisshownin-Figure -1 as attached to the nose.section 11| di :presentday engines `so that the propellers canbe usedfor badly 'needed war production 'without fdelay, or waste ioftime for-ehangesfnf presentfday equipment. 'The particular .designIiftheparts-'shown tcrillustratefth'e applicationuaf-'the-'lnventionwould obviously' lne-.quite uiflerent'but rior xhe'uesirability oimaking '.these adaptalletb '-ettting engine n'ose sections .Figure 2-sshcwnwithout .saidnose Asection J l and itis of course :self-evident:that 'saidrnose secticnican rreauily .be built to accommodate thecomparative simple "transmission 'par-ts tor foperatlng this Pnewcontrollable .pitch propeller. ins the-.few engine partsl'iousedin'saidpI-'es'ent day -nose sectionlreaulyrt my ionlnsrts as plainly as shownin Figurel.

rim important feature-'f my '-mventionrom'la militarystan'dpuintliesdnfthefat that thevery important and *vulnerable:electrical fop'erting p'artshave beenre'm'oved -from-thefmuh expsednose :'sectionfwliere '-ireviou'slykn'ownl'eotrically operatedrn'opell'crs have Iliad :such rparts. Paocording to mylnventiou,'tl1`ese lpa'rts fare nw placed iinithefcockpit wneresthey areuow'iundcr the constant fobservtionior lthe aviator-andn hand -tcontrclhis `provided vso that 'under tfighting conditions whereany-'fthefcotrolzpart may'be destroyed the laviatr Icann keepy'ing byftilhg the 'hand' eontrolanuthls 'enablesfhim'tomke'a lsafe landing.

Myimproved#transmissionrrfcomprrsesnuanu l@ 'applicabile 'by meansdffsdmll tl'fo'rllielllistingfncsesection llicritnezpiue. bestshuwn inFigure 2. this casing providesfeirrmksfatm and imo 'Stor the' upperandlowershafts'm wilifn are ecnnectedfbyr a j"gear-Strain Y-ccnrp'risizmuitermediate gears-mand WGAVlHhKare-respeuttvy mounted upon the shafts94 so that such shafts turninlunison.

:Each v'of' the "shafts et carries twc lpinicns 193. une several pinronsrelug *properly scented to mesh with Y lfour racks 92 v'connectedftc'ithe nonrotative "outer-race J9|! 611s comoste fantiitctionliearln'g s'et "through :Wllhmtion A is l'transmltte fto the l'pressuredisk *8U VTor actuating Ethe blade ffetnering :racks AIlll. 'Thencnlrtatile cuter race You is rurther Vflammea 45in itsaxlalreciprocation by the rods |03 and |03' (Flgt'lrer).`

connection Belwin-en cuter race 90 and the pressure pleiteYcubymeans'o'r rol1ers ira-each of vlich is provided 'wlth"'lts`-own'ahtiiltfon bearingfmcuntirfg 'uponftue pressmefpiatetumuis-prferatilyengageiin thesunlarcumml 13b provided by the'cterfraceBfsishown in Figure 18. Each roller L4mi actually ccmprisesthe outerra'ce of an= indi'iiduabllbearmg, the inner race'of which is mountedoniaitrunnion flhving its reduced"ends :fegageiinbures -T28 inthepressure plate 811, and 'a'complementary cage ring [29 (Figures"I'I'arfd 18). "If fdesired, friction-may be somewhat r'e'dueed .'bytapering the 'outer race of the "roller f'to fit 'a'comr'ilemeritarytaper 'at I3l intlie channel 30 ofthe outer race or rlngfSD.

Th'e composltearti-'lrictlon 'driving bearingln actual practice has an'oter fdiameter o`f .only 17V, inches, but is 'adapted"to.'darry anendivse thrust load of '450D 'poun`ds,'iis`ing`tw`lve small bail bearingunits |26. This requires only about one-fifth of the width of a moreconventional ball bearing to carry the same thrust. Moreover, in theconventional ball bearing, balls 11/2 inches in diameter would berequired, and the breaking of any one of these would destroy thefunctioning of the propeller, whereas in the construction disclosed,ifany one of the small rolling bearing sets is out of order its race willsimply slide in the o uter race |30 of niv composite bearing withoutrendering the feathering mechanism inoperative.

In addition to the safety factor above noted, it may also be mentionedthat in the space between existing nose casings and the hub location onexisting propeller shafts there is no room for conventional ball bearingstructures such as woulduse lyg inch'b'alls to transmit the necessarypressure. It is only by this special design of ball race as hereindisclosed that I am able to provide the necessary transmission mechanlsmin the space available.

Itwill be apparent that bythe arrangement described any rotation .ofshafts 94 is immediately translated by means of the pinions 93 and theracks 92 into an axial movement of the outer race ,90, such axial.movement being communicated through the bearing structure |26 to thepressure plate 80 and thencefby means of racks 8| and plnions 85,again-translated into feathering rotation of the respective blades upontheir respective axes. Themechanism described is extremely sturchr,simple, and effective, and the disposition of the cross shafts 94 issuch that they may be fitted around the existing nose section of presentday airplanes without interference with any of the existing structure.The only requirement is that transverse openings be bored into theexisting nose casings 1| to receive these shafts and their bearings.

So sturdy a mechanism requires no protection but. it may be enclgsed forstreamlining purposes andfor dirt exclusion by a housing |60 (Figure l).v

The power for operating the actuating connections thus far described maybederived in a varietyof ways.A But I have chosen, forillustrativepurposes, toshow the power communicated to this mechanism bymeans of another rack lll which-extends from the pilots compartment tomesh with. a` pinion |35 on a shaft |39 connected toone of the gears|35' -in the gear train. which provides connection-between shafts 94(see Figures l and 2).

Thus, inmy preferred organization. there are three stages oftransmissiomeach involving rack and pinion. In the rst the reciprocatingmotion of the rack Hl, engaging pinion |35 is used to rotate lshaft|38'. In the second rack and pinion stage, the rotation of the shafts 9d(gear connected with shaft |38) is used to reciprocate the racks 92.This motion, communicated through the outer race 90 of the anti-frictionbearings |26 to the rotative pressure plate 80, reciprocates the racks8| in the third stage to eiect feathering movement ol' the respectiveblades.

The hollow steel blade structure is provided to meet the needs of asturdy pitch adjusting propeller with power and size adequate to servelarge military and transport planes. The structure and its method ofconstruction are adapted considerably to increase the rigidity andstrength of the blades with particular reference to their ability towithstand combined torsional and centrifugal strains throughout theblades, but especially in the root section thereof. The various features82 of the blade and its methocl'of manufacture are shown in Figures 3 to16, inclusive, in addition to the partial disclosure in Figures 1 and 2.

Figure 3 shows the assembly of the root of the blade mounted in the bore|08 of the hub socket |05 as above described; the core shaft |6| has ataper |62 to conform with the tapering form of the spar |10. The sparpractically forms a continuation of the shaft, being mounted thereon byplug welding |15' (see Figures 4, 5 and 13) through punched slots |14,|15 formed in the blank |16 of Figure 11, which is later shaped tocomprise a complete spar as shown in Figures 1|), 10a, 5 and 13. Figure12 shows a half spar formed from the half blank |11 and used in theprocess of joining the two half blades |94, |95 by arc welding as shownin Figure 4, where the two half blades are held rmly in mutuallyinsulated carriage clamps of an arc welding apparatus, each beingespecially prepared with circular sections 20| and respective blocks 203fitting thereto, and being adjustable in slots 2|1' for the purpose ofaccurately setting the respective blade sections, all being adjusted tothe common axial center 2|2, of which two are shown; namely section 4a'and 5a.

The respective adjustment of the latter is shown in dotted lines 204,204. For repetition work at the same setting the bolt 201 is opened andthe upper linked portion 2| I is swung open as shown by arrow 208 fortaking out a welded propeller and inserting two other half bladeswithout changing the respective section blacks 203, 203. For clearnessof presentation only one clamping carriage device is shown while anotherlikeclamping apparatus is mounted on the slide |98, being moved on theslide rails |19 mounted on the bed for the purpose of accurately holdingthe two half sections for arc welding, for which object the blade edges|19 are somewhat extended so they can fuse during the application of thecurrent on wires 209, 2|0.

The hollow spar has the further object oi receiving the welding grit andthe provision oi' having an openl bore |63' in said core shaft andcontinuing from the root to the tip of the blade, is for the purpose 'ofremoving all loose grit after the arc welding. Thereafter I insert asuitable quick hardening paste or coating of tar or pitchlike substanceVfor arresting remaining particles that could not be removed even bysuitable power driven tools. This pitch coats the interior inaccessiblesurface where such grit may be lodged, thereby anchoring the gritagainst displacement. Furthermore, the hollow passage |18 of the spar isthen packed with suitable felt or other packing |10' to fully arrest anyparticle from loosening or moving unden'ith'e centrifugal force of therunning propellenjfor the purpose of permanently retaining absolutebalance of it.

To facilitate application by arc welding into the two half blades, thecore shaft 16| is also formed in halves and-screw bolts |92 are providedto properly locate said halves in the welding apparatus and later saidbolts |92 are used for clamping said halves permanently.

Figure 1|) shows a spar die |81 with respective fiat pitch line surfaces|90 as well as an enlarged cross section with a complete spar formedaround` said die and showing the joint |8|. A chucking section |88extends at the root section and centers |88' are applied at either endfor properly operating said die in a suitable machine. An alternateprocedure of securing the hollow blade form 221 to the spar |13 is byspot welding as ascenso 9 showninFigures2,3andlB,andinsaidprocedure thecore shaft remains in one piece and the smaller bore its' is first boredand then the larger one |68 is made, thereby leaving the inner shoulder|92'. leaving stock to receive the bolts |82. o

The plug welding |15', |14' may be by arc welding. The two half blades.as wellfas the bottom seal iti' and the top seal |82' may be put on byspot welding. 'I'he welding apparatus shown in Figure has the samecircular sections Ill for setting the respective blocks 2I3. lit.However, they are preferably of brick or other nre resisting material asin this alternate procedure the Joining of the half blades III, lll isreinforced by brazlng in a brazing furnace, and while it is known thatattempts have been made for lleting certain weldings by soldering withsoft cuprous metal, such usage would not perform the function of unitingmy two half blades into a solid unit and to stand the strain on thejoint.

The sectional setting of the half blades in both procedures of weldingis alike as shown in the setting of section 4b and 8b. Both of thoseshown. as well as the entire series required by the whole length of theblade (see Figure 7. sections c to h) have the same axial center 2li,and the entire series is permanently adjusted in the respectiveapparatus and after finish welding of one blade the setting is opened byloosening the bolt 201 and the lock 2M. Then. turning the lock outwardin the direction of arrow 2li, the entire section 2| I of the apparatusis turned open in the direction of arrow 208 without disturbing thesetting of the blocks lf3. Ill. and the finished blade is taken out andthe next two half blades set in. It will be noted that in this apparatusthe blade is on edge and is supported at the bottom with the wedges Il!while the top half is held in place by links 2|.. which supports are ofcourse applied to all sections in order to dennitely set the correctpitch of the blade before welding.

It will, of course, be understood that the clamping apparatus shown inFigure 5 is dimlicated at intervals throughout the length of the bladeso that all portions ofthe blade are rigidly supported in the properposition before welding or bracing are undertaken.

When the brazim material in the form of wires 224 is set in place asshown in Figure 5, the struc ture is suitably'heated to brazingtemperature for the purpose of permanently brazing the two half bladestogether. as shown in Figure 14, which especially shows the root sectionof the blade with the nllers It! in proper position to nnlsh said rootsection. Said fillers are for the purpose of giving the root section ofthe blade greater strength, to increase the thrust of this section. aswell as to help in the cooling of the engine; a further great advantageis to reduce the strain on the sheet steel in suitably forming the blade(see Figure 8. showing the blank lll for a half blade and in dottedlines the section |83. ill which will form the leading edge as weil asthe trailing edge for each respective blade).

As indicated in Figure 8. the blade blank is wide clear to its shankportion. This requires the use of fillers |69, but involves far lessdistortion of the blank than would be required to reduce it to a smallroot diameter. Moreover, the broad face of the blade continuing clear toits root is of great assistance in propulsion and in cooling the enginewhich drives the propeller. The lack of distortion resulting from choiceof the blank form indicated in Figure 8 makes it l0possibletoextendthebladetoanydesired length. such as would not bepossible to achieve with more conventional blank contours.

This advantage is further increased by split curving the tip of theblade and forming the camber face |82 so that in the folding process itwill strike the pressure face Ill in such a manner that suitable spotwelding lli' will finish the tip as shown in Figure 9. This view alsoshows the folded sections III' and lll' as perspective cross sections,which also show the shaping and suitable mounting of the half spar Ilsby suitable spot welding Ill' in the preparation of the half blades forarc welding them together as shown in Fig. i5. Figure l5 shows thefinished arc welding joint ill, as well as the iillcrs I" and the spotwelding finish Ill', lli. and furthermore illustrates the strong rootIsection of tbe coreshaft III with its bore llt. Bald combiuation ofparts is further brought out in Figure 16.

The control apparatus as shown in Figures l, 2. 19 and 20 has its motiveparts removed from exposed parts of the propeller itself. and its motorM. the worm drive W. and its main rack and pinion transmission R, areplaced in the cockpit. and preferably on the starboard side and at therear of the navigator's seat. thus avoiding manyofthedangersoftheexposedpartsofknown controls being destroyed underghting conditions and in accidents.

A mutable quick reversing motor M has an extended bearing Ill and thepinion 2" is mounted on the motor shaft 2li' driving the considerablylarger spur gear ill mounted on shaft Il.' running in suitable bearingsill and the largewormwflrmlykeyedtosaidshaftand driving the large wormwheel W' keyed to the shaft M1 and running in bearings Ill' andterminating at its top in a reduced section Ill" on which is mounted thecontact pointer ill. At the bottom the pinion ill is keyed to said shaftIll, and the connecting bearings i receive the heavy rack l held insliding contact with said pinion i to receive longitudinal motion. Thefrontpartoftherackslidesinbearingbracket i which has its rear endsuitably mounted to theenginecasingoritsmountingpartsandits forward endextending aside the nose section 1I of the engine.

While it is broadly immaterial how this bracket is supported at itsforward end, it may be carried directly on the shaft III, which isprovided with pinion II! actuated by the rackill reciprocable in bracketill, whereby motion of the rack is transmitted through the pinion to theshaft |83 and thence to operate the transmis sion gears lll', ill. aspreviously described, for feathering adjustment of the propeller blades.

Driving connection to transmission casing 'l'. seeFiguresl,2,l9and20,maybemadefrom diifering angles to best suit the construction ofthe particular airplane and its cockpit arrangements, as thetransmission casing T has a circular flange 'Il which may be adjusted tolocate the point of power input at any desired side of the nose castingll of the plane. For example, Figure l shows the power input pointlocated laterally adjacent the casting. whereas Figure 19 diagrammatlcally indicates the power input as being disposed above the nosecasting of the plane. It will likewise be apparent that by extendingshaft |39 or providing a similar parallel shaft operated by the rackIll, a single such rack may be used to deliver power for thesimultaneous feathering s,4ec, i ce ll of the blades of any number ofpropeller sets operated by different engines.

It will likewise be apparent that, it is broadly immaterial to thepropeller and its control mechanism what kind i motive power orregulating means is applied to the shaft |39 or its equivalent foroperating the rack systems which accomplish the ieathering oi thepropeller blades. It' the rack Ill is used it may be actuated manually,hydraulically, or by means of a motor. All three of these means ofoperation are shown. incidentally, in the disclosure of a preferredsystem of electrical controls.

The manual control is simplest. and is available at all times regardlessof what kind of control may be used.

The motor M on its forward extending shaft 25B" carries a face couplingcollar, and its teeth 283 match the teeth 28| of the hub section 260' ofthe handle 250. Said handle is normally kept out of engagement by thefork 265 ln which said handle is firmly held by ledge 259 riveted tospring 268 and iltting in notch of hub 265 (see Figure Said fork 264turns on stud 284 firmly mounted in base 26B so when said handle isneeded either for testing operations or for emergency use while flying,the fork. after releasing the grip of spring 288. is given a quarterturn, as shown in dotted position 21| in Figure 20, when its ledge 268snaps into the notch 21h and thereby fully releases said handle 280 forhand operation and after engaging the face coupling 2B! 263 thepropeller can be operated for feathering or unieathering action in fullnight of the airplane regardless of any damage which may have disruptedthe automatic feathering operation by motor M. (In

lact. even after the entire electric power service is destroyed.)

The electric controls (Figures 19 to 26), are o! several coordinatedtypes. providing forautomatic governor actuation, manual operation, andsemi-automatic operation They are adapted either for single propellercontrol, or. by simply providing additional connections they are adaptedfor multi-propeller control.

Referring rstto Figure 19, it will he noted that the selector switch Sincludes a casing 229 in which a selector disk 230 is mounted foroscillation by handle 23D'. The casing carries supply contacts 4" and I"which receive current by wires Iii' and 40" from the battery 50. Whenthe safety switch l! is closed. the contacts l" and 9" are energized tocommunicate current to any of the moving contacts carried by theselector disk 230 which may be registered therewith in the oscillationof the disk. f

The disk carries two arcuate series of contacts at diilerent radiicorresponding to the radial positions of contacts 9" and 4" on thecasing. The outer series of contacts has been given even num beredreference characters from 2 to i4. and for convenient reference isreferred to hereinafter as the feathering circuit series. The innerseries of contacts has been given uneven numbered reference charactersfrom i to Il, hereinafter called the unfeathering circuit series. Fiorconvenient reference the same characters are used o indicate thecorrespondingly connected contacts of other switch mechanisms, not onlythrough Figure 19 but in all of the other alternative arrangements.

Above the worm wheel bearing ill' is located a stationary contact diskIIS having contacts bearing reference characters from l to H, connectedby suitable wiring in a cable 69 with the contacts of like number in themanually operable Llil l2 switch S. The shaft l" which turns in bearingH1' extends through the stationary contact disk 2li and carries a movingcontact arm ill having a moving contact il registerable with thecontacts i-Il mounted in the plate.

'I'he function of the switch S is to determine the limits within whichthe feathcring movement of the propeller blades may be adjusted, eitherautomatically or manually. The limitation may be purely electrical. orthe movement oi the contact arm M8 may, by closing appropriate circuitsthrough the contacts on the disk 248, give a visible or audible signalwhich will guide the pilot by indicating that the desired limitestablished by switch S has been reached.

Switch S determines these limits through manipulation of its lever III'which causes the various contacts to register in pairs with the livecontacts' I", l". In each'such pair the even numbered contacts of thefeathering circuit will establish the top limit of the i'eatheringmovement by energizing the corresponding even numbered contact on thestationary contact disk 245. while the odd numbered contacts o! switchS. when energized, will energize the correspondingly numbered oddnumbered contacts oi' the station ary contact disk 2 to determine thelower limit in an unfeathering direction o! propeller blade adjustment.As the driving mtqr M la Operated. whether manually, automatically, orsemi-aun matically, to effect a blade Ieethering movement of rack ill,the transmission of motion to the rack will involve rotation of shaft|61. thereby moving the pointer ill over the face oi' the disk andbringing the pointer contact il into registry with the severalstationary contacts carried by such disk. When the pointer contact I8reaches the highest numbered contact of the ieatherlng circuit (thisbeing the contact l in the' wiring diagrams illustrated) the energizingof contact t will break or reverse the circuit to the motor M. therebyprecluding further feathering movement oi motor M.

Similarlyl when the pointer contact Il touches the lowest numberedcontact in the unieathering circuit. this being the contact l which isshown energized in the particular examples illustrated. this willrepresent the lowest limit oi movement of the blades in an unfeatheringdirection, and the motor M will be either de-energized or reversed toprevent further unfeathering movement (in either case a signal may beenergized to indicate the respective limits without actually arrestingmotor movement or reversing it, ii desired).

By shifting the hand lever 23|' o! switch 8, diiierent pairs of contactsmay be en as clearly indicated in Figure i9. 8 and li may be registeredwith stationary contacts l" and l", or contacta 2 and I may beregistered with stationary contacts l" and l". Thus the pilot mayestablish for himself the particular limits which he wishes to beObserved under any given conditions.

The governor G (Figures 19 and 20) has the important advantage that itsoperation involves very little frictional resistance, being electricalin operation. As illustrated in Figure 19, the governor casing isdivided into two parts, the lower section 212 containing the rotatingparts connected to the engine by bevel pinion 215, such philou operatingshaft 2N running ln bearing 213 and carrying disk I".

On such disks the lugs 211 pivotally support the weighted bell cranksil! on fulcrums at 218. The inwardly projecting arms of the respectivebell ergizfed,l Thus, contacts- 2,4%, i eo cranks bear on the outer raceof a ball bearing 280 which turns freely with the bell cranks as theparts rotate. The heel 211 of each bell crank strikes the disk 216 tolimit the outward throw of the weights and to preclude them fromstriking the casing. AIn the upper section of the governor theelectrical contact parts are located. and moving parts have endwiseaxial motion substantially free from friction and from the diillcultiesencountered in attempts to provide governor control of hydraulicsystems.

A tubular member 2N to which the inner race of bearing 283 is connectedis vertically slidable upon a guide rod 214 which is adjustable in theupper section oi the governor casing and has at its lower end a headlimiting the downward movement of the governor responsive tubular member2M. At its upper end the member 2li has a wedge-shaped point 285 whichbears upon the biiurcated lever 281. This lever is pivoted at 288 to thecasing and is provided with a saddle engaged at 282 which is urgeddownwardly by a compression spring 295 adjustably seated in the screwplug 294, such plug being threaded into the casing and nxed by a plugnut 291 in any desired position of adjustment.

At its free-end the biiurcated lever 201 carries a contact "d whichmoves operatively across a terminal head having at least two stationarycontacts la and sa. The moving 'contactor Itd is energized bv a suitablecurrent connection to the battery il. The stationary contact la isconnected to the motor terminal 33' which energlzes the motor foroperation in a direction to decrease propeller blade pitch while thestationary contact 9a is connected to the motor terminal 32', wherebythe motor is energized for operation in a direction to increasepropeller blade pitch. In operation. any increase in motor speed will becommunicated through the bevel gear 215 to the governor weights. therebycausing such weights to swing outwardly against the compression of theadjustable spring 295, thus raising the sleeves 284 and moving contactor35d into engagement with contact sa, thereby causing the motor tofunction to increase propeller blade pitch. The increased pitchincreases the load to which the motor is subject, thereby tending toslow the motor down. The motor M will continue to function in thedirection oi. increasing blade pitch until the increased loadaccomplishes the result of slowing the motor down, whereupon thegovernor will respond to the decreased motor -Ill speed by allowing thegovernor weights to swing inwardly in response to the pressure of spring295 and the moving contactor 36d will move out oi' engagement withcontact 9a, thus deenergizing the motor.

When the engine speed drops below a predetermined point. the contactor36d will engage contact la and will remain in engagement with suchcontact for a period suiilcient so that the operation o! the motorenergized by engagement of such contacts will decrease propeller bladepitch until the propeller load is decreased soiliciently so that theengine will resume normal speed, whereupon the shifting in the positionof the governor weights will break the engagement of contactor 36a withcontact 4a, thus deenergizing the motor.

Connections to the rotary switch having contact lever |48 operated bythe rack which shifts the propeller blade pitch may be made as indicatedin Figure 19 to enable such switch to function as a limiting switch tolimit the extent i4 of motor energization in either direction inrespense to governor movement.

Figure 20 shows a modified driving arrangement'and hookup including analternatively usable form oi' governor. and further including adesirably usable feathering indicator for visually showing to the pilotat all times the exact pitch of his blades. the indicator being usablewith any of the various systems herein disclosed. Figure 20 is partiallya mechanical view of the parts involved and partially a diagram, someoi' the parts illustrated mechanically being also illustrateddiagrammatically in order to show their electrical connections.

The governor is provided with a shaft I1! to which pinion 311 isconnected to receive motion from the airplane engine. In the rotationoi.' such shaft the weights 313 are moved outwardly upon their togglelever system 310, 31|. 31|' against the tension of the connecting spring423. in the usual manner. The outward and inward movement o! the weightsis communicated through a swivel head IBB to a screw 40|. which isthereupon moved upwardly and downwardly in a guide sleeve to osciliatethe nut 40! which serves as an actuator for the movable contactor of aspecial switch presently to be described.

The governor switch comprises lower and upper dielectric terminal headslil and 35i, which' are identical in their arrangement ot contacts, thelower series oi contacts in the terminal head SII being ieatheringcontacts and the upper series oi contacts in terminal head lll beingunfeathering contacts. Typical contacts used for feathering are marked40m and Mln, both in the cross sectional view and in the correspondingdiagram. Typical unteathering contacts are marked Ip and Nq in terminalhead 38|, as illustrated both in the cross sectional view and in thediagrammatic view in Figure 20.

It will be noted that in each terminal head there is provision for arelatively large number oi' contacts. In actual practice some 24contacts may conveniently be used. Alternate contacts are connected todiiierent wires. Thus the contact q is connected to the lead "c, whilethe contact 40p is connected to electrical lead 40d. alternate contactsbeing likewiseconnected to opposite electrical leads so that no twoconsecutive contacts are connected to the same electrical lead.

The contacts in the lower terminal head Ill are similarly arranged,contact n beingconneeted to electrical lead 4th. while contact 40m isconnected to electrical lead IM. Throughout the series of contacts inthis terminal head the alternate contacts are connected to diil'erentelectrical leads, no two consecutive contacts being connected to thesame electrical lead.

Between the two terminal heads operates a contact carrier serving bothterminal heads alternatively according to its direction of oscillationwith the nut IBS. The carrier and contact arrangement are illustrated indetail in Figures 23, 25, which. although showing a different type ofgovernor. use the same contacting switch. In each case there is a leverarm 380 projecting radially from the nut lill, at the end 0f which ascrew 355 holds a rocker 354 oscillatably about the screw. and having arocker arm carrying a double ended contactor 356, the length of which isnot quite equal to the spacing between the terminal heads so thatthe'contactor 356 may be engaged with either series of contacts in therespective terminal heads according to whether it is raised or loweredabout the screw 35! as a pivot or fulcrum point.

Depending from the rocker Ill is a ball-headed lever 380 socketed inadrag disk 384, which is irictionally engagedwith the surface oi' abraking member 385, offering only sumcient resistance to the rotation ofthe drag disk 36! so that as the nut 40! oscillates the contacterassembly in one direction orsthe other upon the tennlnai heads the dragoi' the disk 364 acting through the ba1l-headed lever 180 will oscillatethe contactor 358 to engage either theupper or the lower series ofcontacts in the respective terminal heads.

Thus. as the engine accelerates to move the governor weights 313outwardly, such weights. pulling downwardly on the screw 40B, willoscillate the nut IBB to rotate the contact assembly counter-clockwiseas indicated by the arrow 4i3 in the diagrammatic illustration of thegovernor switch in Figure 20. In the course of such movement theball-headed lever 350 will communicate motion to the drag disk 364, theresistance of which will oscillate the contact carrier 354 in such a wayas to positively engage the contactor 356 with the contacts 40m, n ofthe lower series in terminal head 350. The supply wire 36 from a sourceof electrical energy. here illustrated as a battery 6l, is connected tothe moving contactor as shown in Figure 20, so that the engagement ofthe contacter with the successive contacts oi' terminal head 350 willselectively energize such contacts in sequence. This; through mechanismpresently to be described, will energize the motor M to increasepropeller blade pitch in successive increments, each energization oi aparticular contact accounting for a specinc increment of advance of thepropeller blade pitch.

The connection oi' the motor M through pinion 251, gear 249, worm W andworm gear W' to the shaft t41, whose pinion |45 actuates rack |44, hasalready been described in connection with Figure 19 and is identical tothe arrangement there illustrated. Coaxial with the shaft |41 is a motorcontrol switch which. in many respects.

is similar to the governor switch just described.

The motor control switch is illustrated mechanically in side elevationin Figure 20 and is also shown schematically in plan, to illustrate itswiring connection. It includes an upper terminal head 353 and a lowerterminal head 352, each having a series oi' contacts corresponding tothe contacts in like series in the terminal heads 150 and 35i ot thegovernor switch. The typical contacts in the series mounted in the upperterminal head 153 are designated 40s and "t, while typical contacts inthe series mounted in the lower terminal head 352 are designated withreference characters 4dr and 4Ilq.

As in the case of the governor switch, alternate contacts are connectedto dliierent wiring leads, the contact 40o. and other contacts similarlysituated, being connected to wiring lead 40e. Contact 401', and othercontacts similarly situated. are connected to wiring lead Illf. Theouter wiring lead 40e 0i' the lower terminal head 352 o! the motoroperated switch is connected to the wiring lead 40h of the outer lowerterminal head oi the governor operated switch. while the inner wiringlead 4t! of the motor operated switch is connected to the inner wiringlead 40a of the governor operated switch.

Similarly. in the cases of the upper terminal heads of the respectiveswitches, the outer wiring lead 40g oi the motor operated switch isconnected to the outer wiring lead 46c of the governor operated switch.and the inner wiring lead 4BR of 16 the motor operated switch isconnected to the inner wiring lead 40d oi the governor operated switch.Thus the corresponding contacts in both terminal heads of the governorswitch are connected to the similarly situated contacts in both terminalheads of the motor operated switch.

In the motor operated switch, however, there are two separate contactorsindividual to the respective terminal heads so that the motor operatedswitch is actually two separate switches. Contactar 4l8, whichsuccessively engages the ilxed contacts oi the lower terminal head 352of the motor switches has a wiring lead 34h for operating the motor M ina feathering (pitch increasing) direction.

The upper contacter 4I l, successively engageabie with the contacts ofthe upper terminal head 353. is provided with a wiring lead 36a whichenergizes the motor M to actuate the blade adjusting mechanism in adirection to unfeather or decrease the pitch.

Since the power requirements oi' the motor M will normally be greaterthan should be handled by the brushes oi moving contactera ISI of thegovernor switch and 4li and lil ot the motor operated switch, I preferto operate the motor directly from the power source itl through relayscontrolled by the wiring leads a and Nb. above described. Thisarrangement is therefore illustrated in Figure 20.

The 'wiring lead 38a from the feathering contactor lill of the motordriven switch mechanism is connected through the relay coil 42S to thenegative side of the battery Il. which, i'or the purposes ofillustration, serves as a power source. When energized. the coil 42|attracts the relay armature 426 to move leitward from its normallycentered position, the pair oi' relay contacts comprising the movablecontacts 421 and 42|, these being directly connected with the powersource. contact 421 being negative and contact 42| positive. In thecourse of their leitward movement these contacts respectively engage thestationary relay contacts 420 and 4" to energize the motor terminals 4liwith positive current and 4I! with negative current from the powersource. At all times when switch 4 is closed the eld coil 433 of themotor is energized.

When the moving contactor or brush Ill moves onto a dead contact. thusdeenergizing the electrical lead 36a and the relay coil 425, the relaycontacts 421 and 418 will move back to their normal central position.toward which they are biased, thereby opening the circuit to the motorbrushes.

When the feathering contacter 4i tot the mo tor driven switch engages acontact which is energized by the governor switch, current will becommunicated through the electrical lead "b to the relay coil 438.thereby attracting to the right as viewed in Figure 20 the relay amature426, and thereby engaging the movable relay contacts 421 and 42! withthe relay stationary contacts 43B and 438, respectively.

This will place the motor brush terminal 43| in direct connection withthe negative battery terminal and the motor brush terminal 432 in directconnection with the positive battery terminal, whereby the motor isreversed and caused to operate in unieathering direction.

The relay not only enables the use oi a motor M which has greater powerthan could be energized directly through the governor and motor drivenswitches, but it also makes it possible to l? energize any number oimotors M from such switches.

The operation by which the respective contacts ot the motor drivenswitch are energized to operate (through the relay. i! desired) themotor M in one direction or the other will now be described.

In operation, one terminal of the current source 50, being connected bymeans oi conductor 36a to the contacter 35i of the governor switch, maybe engaged either with the contacts of terminal head 350 or the contactsof terminal 35|, according to the direction in which the governor switchcontacter is actuated by the governor weights in response to engineacceleration or deceleration.

If a contact (for example contact 40m), oi the lower terminal head lilis engaged in respouse to engine acceleration. the battery current willbe communicated through such contact to the lead lla, thereby energizingthe corresponding lead lle of the motor switch and the alternatecontacts of which u is representative. The lower moving contactor U6 ofthe motor switch, being then engaged with one of the alternate contactsof which s is an example, will receive battery current therefrom andwill communicate such current through the conductor 3B to the relay coil2l to close a circuit from the negative battery terminal to the motorterminal 432 to actuate the motor in a propeller blade ieatheringdirection. However, the same motor induced movement of the worm wheel Wwhich effects ieathering adlustment of the propeller blades will alsoelect a movement o! the contactors oi' the motor switch, thereby movingcontactar Il from engagement with a contact of the l: group toengagement with one of the alternate contacts of the llt group. Sincethe conductor Il! is not now energized from the governor switch, it willbe apparent that the current supply to the motor will be broken and themotor will be broughtto rest after but one increment oi' advance.

In actual practice this may amount to any desired number of degrees oi'blade feathering movement, but in the device shown approximately twodegrees of blade ieathering movement is accomplished. Any continuedacceleration of the propeller actuating engine will produce a furtherresponse oi the governor weights 313 and further response of thegovernor switch in the direction of the arrow lll in the schematicillustration of such switch. This will move the contactor 356 fromengagement with a contact of the lum group to the next contact, thisbeing a contact of the n group connected to conductor 0b. Conductor lbwill now be energized and will energize conductor Il! and the contactsof the Mir group in the motor operated switch. It will be recalled thatin the last increment of advance of the motor and the blade i'eatheringmechanism actuated thereby, the contactor MS was moved into engagementwith a contact of the Ir group. At that time the motor was brought torest because conductor |01 was not energized. il] being now energized bya further advance of the governor switch, the motor M will now beenergized through conductor 38a, which will renew the motor operation ina blade ieathering direction for a further single increment of advance.At the conclusion of such increment of advance contactor ll' ot themotor operated switch will pass from engagement with a contact of theIllr group into engagement with the now deener- 18 gized alternatecontact o! the 40s group, thereby again bringing the motor to rest atthe conciusion of such single increment of advance.

When the propeller actuating engine decelerates, thus permitting thegovernor weights 313 to move inwardly, a reverse operation occurs. lnwhich the drag oi the disk 364 shifts the contactor 35i of the governorswitch into engagement with the contact series of the upper terminalhead 35|. described except that each successive increment of motoroperation occurs in a blade unfeathering direction. in which the angularsettings oi the propeller blades are progressively decreased. In everyinstance the same movement of the blade adjusting motor whichaccomplishes blade adjustment in response to the actuation of thegovernor switch will also eect a simultaneous movement oi the motoroperated switch to break the circuit at the conclusion of such incrementof advance, and to establish a new circuit through which blade operatingmovement oi' the motor may be effected in either direction when furtherchanges in the position of the governor switch occur in response toengine acceleration or deceleration.

If desired, a. manual control for the motor M may be arranged for usealternatively with the automatic control as above described. This may bedone very simpLv by providing the control lever C of the plane with aswitch structure including a't I3 a three-way switch connected in theline 36a of the Vgovernor switch, and also connected to the handoperated push button switches M and l5, the arrangement being such thatin one position of switch I3 the push button switches 4I and l5 will besupplied with current, while in another position of the switch 43 thegovernor switch will be supplied with current.

If anything happens to the governor switch, or, ii for any reason thepilot desires to take over the automatic control and adjust thepropeller blade pitch to suit himself, he may do so by cutl ting oiI thegovernor switch to energize switches u and 45. Manually operable pushbutton switch 4l is connected by a conductor 0i with relay coil 635.whereby the motor M is energized for unfeathering movement. Similarlyswitch 45 is connected by a conductor III with relay coil |25. wherebymotor M is energized for feathering operations. When the hand operatedswitch is in use. the automatic control being entirely cut out. themotor M will operate in a featherlng directon as long as the operatordepresses the button of switch 45, and will operate in an unfeatheringdirection as long as the button of switch 4l is depressed.

In any of the constructions herein disclosed it is considered highlyadvantageous to employ a gage or meter for indicating precisely thepitch angle of the blade or blades subject to control. Ihe rack bar IMbeing directly connected with the mechanism for shifting the pitchposition ot the respective blades, it is conveniently possible to applyto such bar a. separate rack 325 engaged with a pinion 32| on a shaft322. which, extending through bearing 12|, is connected by miter gearingat 32B. 321 with an indicator shaft 329 carrying an indicating symbol orpointer 338 which may take the form of a chord section of the propellerblade.

The lower margin of the pointer or indicator 330. being substantiallyrectilinear, may represent the pressure face oi such a blade, and it mayThe operation is identical to that already bevel gear 330 which outsideof the stationary sleeve 333 through which be made to move across asuitable dial 333 bear lng calibrations 334 in terms of degrees orotherwise, such calibrations indicating to the pilot at all times theexact Position of his propeller blade or blades subJect to the control.Obviously the calibrations may be in terms of degrees or may be in termsof arbitrary symbols indicating relative pitch. l

In any of the devices herein disclosed it is desirable for accuratecontrol that there should be no appreciable overrun of the motor M andits driven parts. At least the motor should be brought to rest in apredetermined interval after it ls deenergized. This may conveniently beaccomplished by a friction brake mechanism iilustrated in Figure 22applied to the motor driven gear 253. A brake disk 252 bearing againstthe face of the gear is engaged by pins 25| which hold such disk againstrotation. A spider-shaped spring 254 is engaged at 249' by a lever 243pivoted at 250 and subject to adjustable engagement at its end by anadjusting nut 248 or screw 258. The lock nut 243' will hold the nut 248in any position to which it is set to apply exactly the desired frictionto bring the parts torest at a predetermined point followingdeenergization oi the motor M.

It may be added parenthetically that the governor switch and the motoroperated switch may diil'er in respect o! the overlap of the movingcontactor with respect to the stationary contacts. In the'governoroperated switch there should be no overlap. There should be a deiniteinterval between the stationary contacts which is greater than the faceof the contacter so that the contactor will denltely clear one contactbefore engaging another. In the case of the motor operated switch,however. it ls important that the switch should never be left whollyopen. As soon as the contactar clears one contact it must be positivlyengaged with another. and actual overlap is immaterial.

Figures 23, 24 and 28 illustrate a further moditied form of governorhaving certain advantages. The engine driven shaft is indicated at 313.and the weights 311 are carried by a toggle lever set 310, 31B', 31|,31|' as described in connection with Figure 20. However, in thisconstruction the toggle levers 310. llt are connected through ananti-friction swivel bearing arrangement 368, 363, 310, 310' to avertically movable rack bar 313 secured to the inner race of theanti-friction bearing by a nut 313. This rack bar has rack teeth at 332meshing with a pinion 333 on cross shaft 334. such cross shaft beingprovided with another pinion at 33|. driving gear 39|! to operate thebevel gear 33|. This bevel gear meshes with is rotatably mounted on thethe rack bar reciprocates. and in which the rack bar is non-rotatablykeyed at 394.

The hub of gear 380 carries the arm upon which the rocker 354 carriesthe oontactor 353, as previously described. 'Ihe ball-headed lever 380depending from the rocker engages the friction disk 364 which bearsagainst a stationary friction ele ment 365 (such as a piece oi' cork)which will provide the required coeillclent oi' friction to resistmovement of the disk only suillciently to assure the oscillation o! therocker 854 according to whether the gear 330 is moved in a clockwise ora counter-clockwise direction.

A very sensitive adjustment is provided for this governor by means oithe spring 33B which is wound, as clearly shown in Figures 23 and 24,

upon a pulley 385 mounted on shaft 334. The end of the spring is securedat 381 to the pulley. After passing at least part way about the pulleythe spring is carried out of the governor casing through an opening lillto an anchorage which may be provided by a cord 4I! wound upon amanually controllable pulley 420 adjustable on shaft 12| by means oi ahandle 422. The so-called booster lever or handle 422 may be adiusted bythe pilot as desired to vary the tension of spring 286, thereby varyingthe relative position of the propeller blade pitch at any given enginespeed.

As contrasted with ordinary governor springs. which are usually shortand heavy. the greater elasticity and sensitivity of the elongated typeof spring provided at 386 gives a much more sensitive and even control.

It will, of course, be understood that any desired governor may be usedin the automatic control indicated, but it is believed that governors ofthe specific types disclosed have advantages making their use desirable.

Where it is desired to apply my ieathering control mechanism to planeswhich are already provided with governors organized for the control ofhydraulic servo-motors, I may connect such a servo-motor as indicated inFigure 21 directly to the rack bar i4! for the hydraulic operationthereof. I have shown the servo-motor 32|) provided with two inlets Bsindicated by arrows 33| and 331 to the opposite ends of the cylinder inwhich piston 32| operates. such piston being connected to the end of therack bar HI by means of a nut 324' applied to the threaded end 324 ofthe rack bar. The piston may have suitable packing at 322. Therespective inlet ports 335 move as a slide valve in the valve casing330'.

The placing of the valve members upon the spindle is such that when thevalve is in one position, as indicated in Figure 2l. the inlet port 332to the outer lace 323 of the piston is open, while the outlet port 331is open from the other end of the cylinder. When the valve is shifted tothe right from the position in which it is illustrated. it will closeport 332 and port 334 and will open the inlet or pressure port 335 andthe outlet or drain port 33,6, thus reversing the direction of pistonoperation. While it ls broadly immaterial how the valve is actuated. itsstem or actuating rod 328 may be moved hand or by connection to a or anyother desired manner.

It is important to lock the piston in each position of adjustment wherehydraulic operation is employed. I accomplish this by providing rackteeth at 344 upon the rack bar |4i. such teeth meshing with a pinion 343on the shaft of an electromagnetic brake energized by connectionsindicated at 34l and 342. the arrangement being such that the brake isdeenergized when the piston is being intentionally shifted to adiil'erent setting.

It ls also of the greatest importance that provision be made foremergency operation. To this end the shaft on which pinion 343 ismounted is provided with a manually operable handle 345 serving the samepurposes as the crank with which I am able to operate the amature shaftoi the electric motors herein disclosed.

In the event of power iallure or other accident, the pilot may controlhis blade pitch manualLv by rotating the crank 345, thereby manuallyactuanarco ating the rack MI. To permit such `actuation notwithstandingthe possible closed position of the valves controlling the ports fromthe hydraulic cylinder. I provide an emergency by-pass valve 339 whicheither drains the iluid from both ends of the cylinder or by-passes thepistons so as to permit of free piston movement in the cylinder duringmanual operatiom/ It will. of course, be understood by those skilled inthe art that various changes and adaptations may be made in the featuresherein disclosed. The device as disclosed represents but one of variouspossibilities in the way of complete variable pitch propeller systemsincorporating my invention. Where I have suggested limitations. theseare merely by way of example, and they may be combined in various waysother than those 'specifically indicated.

In order to summarize the several features of the invention in thecomplete system illustrated. the following list oi their advantages isbriefly stated:

The hub design presents important advantages in that it is of unusualstrength and of unusual simplicity. Unlike many variable pitch propellerstructures, the hub for the propeller herein disclosed is unitary, andis preferably not only unitary but made in one single piece, requiringonly the provision of the several bores and machined bearing surfacesherein described. It therefore has exceptional strength and oifers aminimum of air resistance. It is made with a minimum of labor andmaterial. Any number of blades may be mounted without any fundamentalchange in hub design.

The propeller blade has a great many advantages in the way ofsimplicity. economy of manufactne. lightness, strength and efiiciency.'I 'he blade is unique in the manner of its internal reenforcement andthe provision of a shaft mount in such reenforcement to project from theroot end of the blade for its mounting. It is also unique in thespecific manner in which it is fabricated, being made of channel-shapedblade parts each comprising sheet metal folded upon a line representingthe leading or trailing edge of the blade so that the union between theparts is made along the center line of the pressure and camber faces.The blade is also unique in the construction of its tip and its rootportions. While particularly adapted for use in a variable pitchpropeller, the blade is of such a character that it may be mounted inany hub for use' in any type of propeller. variable pitch or otherwise.and its pitch adjustment may be controlled in any manner.

The method of blade manufacture is closely related to blade structureand makes possible the specic features of blade construction abovenoted. The method involves the particular manner in which the componentparts of the blade are pre-fabricated and joined together, including notonly the channel-shaped members which provide portions of the bladefaces, but also the reenforcing or spar sections which are incorporatedwithin the blade and serve to mount the stub shaft upon which the blademay be mounted in the hub. The method is also concerned with eliminationof material unavoidably left by the welding or brazing operations in theinterior of the blades. Such material must be either completely removedor completely fixed as to position. as otherwise it would. whendislodged. destroy the balance of the blade. The method of constructionincludes the removal of all such ma- 22 v terial as is loose. and thepermanent iixation of the remainder, the packing used as a part of thefixation process being variable as to amount. whereby to assist inbalancing the blades against each other.

The pitch varying mechanism is closely related in some respects to thehub design.' The mechanism at the hub includes three racks. the bores inwhich the racks operate being the only openings in the hub other thanthe blade sockets and the mounting bore. The construction is such thatthe number of racks may readily be varied according to th number ofblades to be operated. the operation :in all instances being identicalregardless of such number. The pressure plate which operates the severalracks in guided upon a portion of the propeller hub and is moved by ahighly novel swivel bearing organization, which includes rollers havinganti-friction supports on the pressure plate and operating in an axiallyreclprocable race, whereby axial motion is communicated to the pressureplate during its rotation of the hub. The actuation of this race, inturn, is preferably likewise accomplished by racks moving axially of thepropeller shaft at opposite sides thereof and activated by pinion shaftswhich are so organized and disposed as to permit of their installationin the very limited space available between the propeller and the noseof the plane in existing equipment. By using'an indexible mount forthese rack actuating pinion shafts and their intergearing I am able tocarry my operating connections from the cabin oi' the piane to themechanism at the nose of the piane at any desired point. and I locateall of the power or manual controls in the cabin where they can readilybe protected. thus leaving no delicate electrical wiring or electricalcontrols at the vuinerable nose of the plane.

Electrical controls. preferably located as above indicated. in the cabinof the plane. meet almost any requirement in that I have shownarrangements for automatic control. for manual control, and for limitingthe automatic control to function either in predetermined increments ateach energization, and. if desired. to function over a predeterminedrange, within limits fixed by the operator. In order to effectuate mypurpose in these regards I have provided novel types of switches havingmovable contactors or brushes which automatically shift from one seriesof ilxed contacts to another according to the direction of movement ofthe part from which power is d: rived. I have also devised new circuitconnections so that the circuit may in each instance be closed by thegovernor operated switch and opened at the end of a predeterminedincrement of travel by the motor operated switch to limit the propellerpitch adjustment to the desired increments without using a separate wirefor every contact, such as might otherwise have been required.Regardless of whether the controls are electrical or hydraulic. I haveprovided means.

normally ineiective, for operating the pitch adjusting mechanism by handin the event of power failure or accident to the control mechanism.

The indicator is an extremely important feature for experienced pilots.as well as being oi great assistance to those who are learning.Irrespective of the type of ieathering propeller or the actuatingmechanism therefor. or the controls. the indicator is provided withmotion transmitting connections which cause its pointer to move inacadien exact accordance with the pitch movement oi' the blades so thatat all times the blade pitch is shown on the indicator dial. Theindicator has particular utility in the combination disclosed, inmmuchas the mechanical actuating connections which adjust the blades as topitch actually extend into (or from) the cabin of the plane. therebyfacilitating the direct application of the indi cator thereto.

Improved governors are an important feature of the invention and may beused for purposes other than the particular propeller system hereindisclosed. Not only are the governors susceptible of separate use, butit will Vbe understood that either of the governor mechanisms disclosedhereln may be substituted for the other in the general organization.

The switches disclosed. and the circuit connections for such switch, areimportant for reasons previously indicated, and, like the governon,these switches may be used for purposes other than the purposes of theparticular propeller control system which comprises the primary subjectof the invention. The switches, however. have particular application tothis propeller system, and the means whereby the moving contactar orbrush of a governor switch may be made to engage selectively either thefeathering contacts or the unfeathering contacts according to whetherthe governor is accelerated or decelerated is a feature of particularvalue. By energizing alternate contacts in sets and connecting the setsas such with similar` alternate contact sets in the motor drivenswitches, I am able to cause the contactors of the motor driven switchesto move in predetermined increments without separately wiring eachindividual contact of one switch to a corresponding individual contactof the other. Thereby I reduce the amount of wiring required andaccomplish great simplification and reduction in cost of materials andlabor. The resulting simplicity is also a great advantage when it comesto repair and freedom from injury during use.

Ielaim:

1. In an airplane propeller, the combination with a propeller shaft, ofa hub mounted on said shaft and provided with outwardly opening bladesockets, blades rotatable upon their respective ax in the respectivesockets and provided with pinions, racks slidable through said hub ingeneral parallelism with said shaft and meshing with the respectivepinlons for the oscillation of the respective blades in their sockets. apressure plate to which the several racks are connected behind thepropeller. an annular member connecting the several racks forwardly ofthe propeller, and spring means biasing the several racks for movementrearwardly parallel to said shaft.

2. The device of claim l, in which said biasing spring means includes aspring and a yieidable stop member acted upon by said spring andposltioned to be engaged by the annular member connecting the racks at apoint intermediate the rack range of movement, whereby said racks aretree of him during a part of their range oi movement and are subject tobias during another part of such range of movement.

3. In a variable pitch propeller, the combination with a hub and a setof blades having shank portions iournaled in the hub for pitchadjustment, plnlom upon the respective blade shank portions. racksreciprocable axially of the hub and meshing with the respective pinions,a pressure plate connecting said racks, bearing means engaged with saidplate and including'a relatively non-rotatable annulus with which saidplate is in bearing engagement to receive reciprocations from saidannulus, a set of racks con nected with said annulus. and means forreciprocating said last mentioned racks in unison, the means forreciprocating the last mentioned racks in unison comprising a pair ofmutually spaced cross shafts extending transversely at opposite sides ofthe axis of the hub, pinlons upon the cross shafts. motion transmittingmeans connecting the cross shafts for simultaneous rotation, and drivingconnections for said cross shafts and motion transmitting means.

4. In a device of the character described, the

mblnation with a propeller shaft, of a propeller hub mounted on saidshaft and provided with rack bores generally parallellng said shaft andwith blade sockets intersecting said rack bores. blade shanks in therespective sockets provided with pnions at said rack bores, racks in therack bores meshing with the blade plnions, an annular pressure plateconnecting the respective racks immediately behind said hub. saidpressure plate being rotatable with said hub and axially with saidracks. a driving annulus for said pressure plate having peripheralbearing connection therewith. said annulus being reciprocable along theaxis of said shaft and fixed against rotation, a set of racksdistributed about said shaft and engaged with said annulus, cross shaftsdisposed at opposite sides of the propeller shaft and provided withpinions with which the racks last mentioned are in mesh, a gear trainconnecting said cross shafts for concurrent rotation, wherebysimultaneously to advance and retract the last mentioned racks, therebyadvancing and retracting said annulus and said pressure plate duringpressure plate rotation, and driving connections for said cross shaftsand gear train.

5. The device of claim 4, in which said driving connections include adriving shaft for the gear train provided with a pinion, a rack meshingwith said pinion, and a remotely located motor having an operating partconnected with said last mentioned rack for the reciprocation thereof.

6. In a device of the character described, the combination with a nosecasing and a propeller shaft projecting therefrom, of a propeller hub onsaid shaft close to said casing and provided with a set of racksreclprocable parallel to said shaft to and from said casing. a pressureplate of annular form connecting said racks and disposed between saidhub and said casing, blades mounted in the hub for pitch adjustment andprovided with pnlons meshing with the respective racks. an annularbearing race surrounding said pressure plate means for reciprocatingsaid bearing race, and anti-friction bearing means connecting saidbearing race with said pressure plate. whereby to transmit reclprocationto said pressure plate during rotation of the pressure plate respectingsaid race, the means for reciprocating the bearing race comprising crossshafts at opposite sides of the propeller shaft, motion transmittingconnections between said cross shafts for assuring their rotation inunison, plnions carried by the cross shafts. and racks meshing with therespective plnlons and connected with the bearing race at differentpoints about said propeller shaft for the balanced reciprocation o! saidrace.

EMIL R. IDCHMAN. (References on following page) REFERENCES CITED Thefollowing references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Bevis Mar. 23, 1915 Peoples et alFeb. 3, 1920 Gove May 31, 1921 Carter July 5, 1921 Shaver May 9, 1922Craft et al Apr. 17, 1928 Bolduc Dec. 8, 1931 Rossi Jan. 5, 1932 NixonMay 10, 1932 Edman May 16, 1933 Crafts Apr. 17, 1934 Number 26 Name DateMichl Aug. 6, 1935 MacCallum Nov. 12, 1935 Gorski Feb. 11, 1936 GarrettJune 16, 1936 Roberts June 22, 1937 La Salle July 13, 1937 Heath Aug.23, 1938 Barsh Feb. 14, 1939 Feigel Nov. 12, 1940 Mullen Jan. 14, 1941Dicks Jan. 21, 1941 Gemeny Feb. 25, 1941 Chilton Apr. 21, 1942 Reiber etal. Aug. 17, 1943 Sahle Oct. 24, 1944 Stevenson Dec. 12, 1944

